Method for producing alloys



ratenteu flpl'. 1U, 1:703

UNITED STATES PATENT OFFICE No Drawing. Application August 8, 1936, Serial No. 95,018

9 Claims.

My invention relates to certain betterments in alloys and their methods of production, more particularly, but not restrictedly, ferrous alloys, such as those containing iron, nickel, and aluminum.

One leading aim of the invention is to provide a novel and improved method of producing an alloy which is substantially free from blow-holes, shrinkage-cavities and other similar defects, which has high coercive properties and which possesses powerful retentive properties for magnetism.

Another prime purpose of the invention is the supplying of such alloys at relatively small cost and by an economical procedure which is quite simple. 1

In one of its broadest aspects, the invention is more generic than indicated in that it provides eflicient means for the reduction of one or more of the alkaline earth metal compounds or the alkali metal compounds.

Alloys containing iron, nickel, aluminum and cobalt have been known for some time, but the cost of the cobalt is an important factor in the production of such alloys.

I have found, however, that all of the advantages of the cobalt may be had, and some important others may be enjoyed, by employing certain of the alkaline earth metals or alkali metals or magnesium, in place of the cobalt, whereby the purifying action of such material or materials is availed of to great gain and service.

I have made the valuable discovery that when strontium as a metal, or any of its oxides, preferably peroxide, or salts, such as its carbide, carbonate, sulphate, nitride, chloride, fluoride, iodide, bromide, etc., is used in conjunction with, aluminum or its equivalent in an alloy such as one containing iron and nickel, the oxide or salt, if the metal itself is not used directly as such, is reduced by the aluminum, and the strontium, when introduced as a metal, or reduced from its salt, acts as a scavenger for the iron and nickel, removing their impurities, such as oxygen, nitrogen, hydrogen, carbon, sulphur, etc., with the resuit that the product is particularly dense and unusually free from cavities, holes, or voids, and has substantially increased magnetic properties when magnetized.

In place of strontium, barium as such, or in the form of any of its compounds or salts, but preferably as barium monoxide, may be employed or calcium or its compounds may be used instead.

Thus any of the alkaline earth metals or their compounds or salts may be availed of for the 5 purpose indicated.

Or, as a substitute for the foregoing, magnesium or its oxides or salts may be employed to produce the same or an equivalent efiect.

Stated somewhat difierently, my present invention concerns certain features of improvement in the treatment of irons, etc., and their alloys, whereby to increase the solidity of, and to otherwise improve the properties of, castings made from such metals, such as the reduction or possible elimination of shrinkage, the avoidance of voids, an increase in magnetic characteristics, etc., and also to simplify the processes employed in producing such castings.

I have determined that in certain types of ironalloys, notably those containing appreciable quantities of aluminum, for example, those having from one-half per cent upwards, are materially benefited or improved by the addition of an alkaline earth metal or one of its compounds, preferably, but not necessarily, strontium or barium or one of their compounds, such as an oxide or salt.

It has been demonstrated that the strontium or barium or their compounds can be introduced either prior to or after the introduction of the, aluminum into the nickel-ferrous alloy, or it may be added to either all, or a part of, the aluminum before the addition of the latter to the alloy, the present preferred method, however, being to add the strontium or barium or its compound in a. .closed iron capsule or other type of receptacle during the addition of the aluminum, which is ordinarily the last of the constituents to be used in making up the mixture.

Apparently, if the strontium peroxide or barium monoxide, for example, is employed, it is reduced to the metal, the latter alloying with the aluminum which ostensibly is responsible for the increased magnetic" properties of the alloy.

As an example of how the invention may be practised to advantage, the following is submitted:

Approximately 926 pounds of low-carbon iron, or steel, such as Armco iron or low carbon steel stamping scrap, and about 420 pounds of nickel are mixed and melted together at a temperature of about 2900-3100 F., whereupon such molten mass is superheated to a temperature in the neighborhood of 3200 R, such increase in temperature being employed to assure adequate and complete melting and mixture of the two ingredients.

Thereupon twelve pounds of ferro-silicon and eighteen pounds of ferro-titanium are added.

One hundred and seventy-three pounds of aluminum having been first heated to about 700 Fahrenheit, which is below its melting point of about 1220 F., is added to the mixture after the latter has been cooled to a temperature of about 3100 F. to prevent loss of aluminum by reason of its volatilization by boiling and gasification, whereupon the mixture is slightly agitated or mixed to obtain adequate commingling of its constituents.

During the aluminum addition, three pounds of strontium peroxide or five pounds of barium monoxide is added. The aluminum reduces the strontium peroxide or the barium monoxide to the metal, and the latter, because of its comparatively great chemical activity, has a relatively high aflinity for the impurities in the mixture which must be gotten rid of if the desired advantages of this invention are to be obtained.

The aluminum itself scavenges the mixture to a certain extent and the strontium or barium seemingly completes or augments the purification, whereby the material, by use of the two, is purified adequately to secure the results sought and further results in a crystallization on cooling very different than when the same alloy is made without such strontium or barium. The molten alloy is poured into a ladle and from this into a mold for solidification and cooling.

Upon fracture of the product, the crystal or grain faces show extreme twinning, that is to say, the assemblage of two or more crystals, or parts of crystals, in reversed position with reference to each other.

The casting is macroscopically substantially free from voids, such as blow-holes, shrinkagecavities, or absence of metal in general.

It has a high coercive force, in that it is reluctant to accept magnetism, and it is highly retentive of magnetism when so charged.

In case it is preferred to use strontium oxide instead of strontium peroxide, then 3.3 pounds would be used in the mixture previously set forth, or if strontium carbonate is employed in place of the peroxide, then 4.5 pounds would be the correct amount to use, it being observed that in each instance the quantity of the metal strontium available for purifying purposes is the same. Other strontium salts on the same basis could be employed.

As has been indicated above, various other metals and their compounds may be employed in place of strontium and its compounds, the comparable or equivalent amount to be used in each instance being a matter of mere chemical calculation well understood.

These various alkali metals or alkali earth metals may be mixed, substituted for by each other, or a large number of them or their compounds added in small proportions of each to make up the required aggregate amount with equally beneficial results.

My invention is not necessarily limited or restricted to the precise procedure or the temperatures or the amounts of ingredients set forth above, since these may be modified more or less without departure from the substance and essence of my invention as presented in the appended claims, and without the loss or sacrifice of any of its substantial or material benefits and advantages.

I claim:

1. The process of making a ferrous-alloy having potential magnetic properties of a permanent magnet including making a molten mixture of iron, nickel, aluminum and a compound of magnesium, said ingredients being combined in any order and in such proportions as to produce an alloy having potential magnetic properties of a permanent magnet.

2. The process of making a ferrous-alloy having potentialmagnetic properties of a permanent magnet including making a molten mixture of iron and nickel, adding to said mixture strontium peroxide, and adding aluminum to said mixture, said ingredients being in approximately the following proportions: iron 926 pounds, nickel 420 pounds, strontium peroxide 3.3 pounds, aluminum 173 pounds, and ferro-silicon (50% Si) 12 pounds.

3. The process of making a ferrous-alloy having potential magnetic properties of a permanent magnet including melting a mixture of iron and nickel, superheating said molten mixture to about 3200 Fahrenheit, adding to such molten mixture a compound of one of the following: strontium, barium, calcium, magnesium, sodium, potassium, lithium, caesium, rubidium, cooling said mixture to about 2900 Fahrenheit to 3100 Fahrenheit, and adding to such cooled mixture aluminum previously heated to about 700 Fahrenheit.

4. The process of making a ferrous-alloy having potential magnetic properties of a permanent magnet, including melting a mixture of iron and nickel, superheating said molten mixture to about 3200 Fahrenheit, adding to such molten mixture strontium peroxide, adding to such mixture aluminum previously heated to about 700 Fahrenheit, said ingredients being in the approximate proportions of 926 pounds of iron, 420 pounds of nickel, 1'73 pounds of aluminum, 3.3 pounds of strontium peroxide, and 12 pounds of ferro-silicon (50% Si).

5. The process set forth in claim 2 including melting the various constituents separately and putting all together in the molten or liquid phase.

6. The process of making a ferrous alloy having potential magnetic properties of a permanent magnet, including king a molten mixture of iron, nickel, alum um and a compound of an alkaline earth metal, said ingredients being combined in any order and in such proportions as to produce an alloy having potential magnetic properties of a permanent magnet.

'7. The process set forth in claim 6 in which at least the major portion of said compound of alkaline earth metal is introduced into the mixture with at least a part of the aluminum.

8. The process of making a ferrous alloy having potential magnetic properties of a permanent magnet, including making a molten mixture of iron, nickel, aluminum and a compound of an alkali metal, said ingredients being combined in any order and in such proportions as to produce an alloy having potential magnetic properties of a permanent magnet.

9. The process set forth in claim 8 in which at least the major portion of said compound of an alkali metal is introduced into the mixture with at least a part of the aluminum.

ROBERT G. GUTHRIE. 

